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RegGuheert
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Enphase M190/M190IG/M215IG/M250 Head-to-head-to-head

Thu Jun 26, 2014 5:00 pm

This morning I replaced nine of the 42 M190 microinverters on my roof with brand-new M215IGs. (FYI, IG stands for "Integrated Ground".) I will replace three more M190s when I have a chance. The M190s which were removed will move to an old array which is sitting in a field. These old inverters are compatible with the 72-cell panels in that array while the M215s are only compatible with 60-cell panels.

Here is a picture showing both of the arrays along with our major electricity consumer:

Image

With this change, I am now in a position to directly observe the in-field differences between the two generations of Enphase inverters. The M215s are now connected to identical PV panels and they are located in a nearly-identical environment as some of the M190s which remain.

Here are some specifics:

PV Panels: Sharp NU-235F3 235W PV Modules
M190 Inverters: Enphase M190-72-240-S12 Microinverter
M215IG Inverters: Enphase M215-60-2LL-S22-IG Microinverter
Latitude: 39 degrees North
Tilt: 30 degrees
Azimuth: 194 degrees

So, what differences do I expect? Here are a few thoughts:

- The M215IGs are significantly easier to install! In fact, I will say installing the M215s was slightly easier than UNinstalling the M190s. (One interesting benefit of the M215s: They use REAL MultiContact MC4 connectors while the old M190s had Amphenol knock-offs which were difficult to mate and unmate from the real ones on the Sharp panels.)
- The M190s have about 11 years left on their warranty while the M215s have 25 years remaining. (I like this part!)
- Based on the investigations I did into reliability, it appears the M215s should be more reliable than the M190s. (Although I will note that my analysis was of the original M215s, not the M215IGs.) After 3.5 years, I have had two (~5%) of our M190s fail. One was replaced by Enphase, the other was "fixed" by a firmware change but now produces about 6% less energy than it did prior to the failure.
- The M215 is *slightly* more efficient. I doubt I will see a real difference here, but we will see.
- The M215 can put out 225W while the M190 can only put out about 199W. This will not have any effect this time of year, but it should result in additional energy harvest in the cold of winter and spring.

I don't have any data yet, since I haven't gotten Enphase to update Enlighten. But you can see what the array looks like by clicking the link in my signature below. You can find a description of the array, some photographs and historical data for the entire array, but not for individual inverters. The nine inverters which were replaced this morning are the nine which are on the top row on the house (the subarray on the right).

I don't expect there will be too much to report until it gets cold, but I wanted to start the thread to get the discussion going. Please ask any questions you may have and I will see if I can come up with an answer.

In the meantime, here is a photograph of the contenders in this battle:

Image

Many thanks to QueenBee for selling me the inverters and getting me great prices on all of the rest of the new equipment!

Edit 1: Added images.
Edit 2: Changed title.
Last edited by RegGuheert on Sat Jul 04, 2015 12:14 pm, edited 2 times in total.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

QueenBee
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Re: Enphase M190 vs. M215IG: Head-to-Head

Thu Jun 26, 2014 8:22 pm

RegGuheert wrote: (One interesting benefit of the M215s: They use REAL MultiContact MC4 connectors while the old M190s had Amphenol knock-offs which were difficult to mate and unmate from the real ones on the Sharp panels.)


Many thanks to QueenBee for selling me the inverters and getting me great prices on all of the rest of the new equipment!
I don't think I've had to disconnect any of the M215IGs yet but I noticed a difference between my phase 1 and phase 2 with regards to the connectors. I don't really remember the specifics and don't really know enough/paid close enough attention to determine if it was the Enphase side or the Canadian Solar side that changed but I had to remove my phase 1 to install a new roof and it went pretty well disconnecting them with the plastic disconnect tool but for phase 2 I had to disconnect a couple panels and man was it difficult. The issue appeared to be that the male part of the latch was not as long so you could push the tool in without causing it to properly push down to release. Good thing the tools come with so many different "teeth" as I ended up breaking a fair number of them fighting it.

You're definitely welcome, anything I can do to help promote EVs and PVs is time well spent. :)

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DaveEV
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Re: Enphase M190 vs. M215IG: Head-to-Head

Thu Jun 26, 2014 11:52 pm

Thanks for the writeup. Did you take any pics of the old/new inverters and your other ground-mount array?

How did you mate the M190 cables to the M215 trunk cable - just a junction box?

BTW, the M215 can work with some 72-cell panels:

http://enphase.com/global/files/Enphase ... bility.pdf" onclick="window.open(this.href);return false;
http://enphase.com/module-compatibility-calculator/" onclick="window.open(this.href);return false;

For example, I have ET solar ET-M572180 72-cell panels and they are compatible with the M190, M215 and M250.

Oh, and just how good of a deal did you get on the components? I need to expand my array by a kW or two!

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RegGuheert
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 7:04 am

drees wrote:Did you take any pics of the old/new inverters and your other ground-mount array?
Not yet. I will try to get some photographs showing the differences in the wiring for the M190s and the M215s.
drees wrote:How did you mate the M190 cables to the M215 trunk cable - just a junction box?
Good question, since this is one of the major differences between the M190s and the M215s. While the M190s are daisy-chained together, the M215s all connect into a trunk cable know as the Engage system. While the M190 daisy-chain system has the advantage of flexibility, the Engage system has the following advantages:

- Engage uses 12 AWG wiring versus 14 AWG with the M190s. This has a benefit of enhanced efficiency. The other benefit is that you do not need to find 2-pole 15A breakers for the Engage system. I had trouble finding these for my system and had to order a box of them from eBay.
- Engage allows you to minimize your wiring length when you use a portrait layout of the PV panels. When combined with the larger wire diameter, this results in significantly improved system performance and/or more flexibility in wiring. With 15 inverters in a single string, the M190 system results in a voltage rise of 4V at the end of the string. That is a nearly 2% efficiency hit! With the M215 with Engage in portrait orientation, you get a maximum voltage rise of 0.63V with 15 more-powerful inverters (and 17 maximum are allowed). In my case, I had limited all of the M190 strings to seven microinverters, which limits maximum voltage drop to about 0.85V. With the change, I will likely be putting ALL 12 of the the M215s on the same Engage cable, which will result in the end of the string having a maximum voltage rise of 0.99V, which is only slightly worse than the 7 M190s.

Anyway, to answer your question, I am completely replacing one M190 string with an M215 string, all the way back to the junction box. I designed this system to have no junction boxes on the roof. There are only four roof penetrations with the junction boxes just below the roof in an open attic which allows me to stand comfortably while wiring. I am also *shortening* two M190 strings from seven microinverters to five and four and then moving the remaining five PV panels over to the M215 Engage cable. I had to purchase a couple of extra positions on the Engage cable to allow me to make the transitions to other rows.

(As an aside, I now realize that I may wish to consolidate the remaining M190 microinverters onto a single string of nine so that I can then have two strings available for the other array. As it stands now, I will have a single string of 12 M190s in the field, which gives a 2.5V voltage rise maximum. I will likely only make this change if I can do it without having to lift any panels. That's very unlikely!)
drees wrote:BTW, the M215 can work with some 72-cell panels:
Good point! And, in fact, my Solarex MX120s likely could work with the M215s, but I would worry that sometime in the next 25 years we would get cold enough here (-10F or so) to cause a problem. It's a bit too close for comfort in this climate. The Sharp modules give me about 5V of margin compared with the Solarex units.

In addition, I prefer to have the more reliable units on the roof, since they are more difficult to access and the panels are about 12 years younger.

Edit: "5F of margin" -> "5V of margin"
Last edited by RegGuheert on Fri Jun 27, 2014 9:45 am, edited 1 time in total.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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DaveEV
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 9:02 am

Sounds like a nice clean install. Yes, the larger and slightly shorter cable of the Engage system can provide slight efficiency improvements. Less cable on the roof is a good thing, too. I know that on my setup I have bundles of wire under each panel which had to be carefully tied to the rails.

Does your layout facilitate center-tapping strings to effectively cut each string-length in half? That's another effective way to minimize the effects of cable length, especially if you use 10GA home-runs, though I guess with a voltage rise of only ~1V, it's not worth doing unless it shortened the cable run.

Keep in mind, though that the not all inverters benefit the same, it's primarily the inverters/panels farthest away from the junction box which benefit. So the 15th inverter in a string might see a significant reduction in voltage rise, the 1st one only sees a minimal difference.

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RegGuheert
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 9:35 am

drees wrote:Sounds like a nice clean install. Yes, the larger and slightly shorter cable of the Engage system can provide slight efficiency improvements. Less cable on the roof is a good thing, too. I know that on my setup I have bundles of wire under each panel which had to be carefully tied to the rails.
Yes, the difference is dramatic! Here are pictures of the old-style M190 install (left) and the M215 install (right) (click to see larger versions):

Image Image

Note the lack of cable ties on the AC side with the M215! I still have a couple on the DC side, but that has more to do with the PV panel than the microinverter. Also note that the ground wire is still there. The PV modules still need to be grounded!

And, to top it all off, this morning I finally saw a picture of how the metal clips are supposed to work in one of Enphase's documents. So I grabbed an old piece of rail and a length of Engage and figured out how it works. Then I ran up on the roof with the bag of clips that QueenBee gave me and dressed the Engage cable for the nine that are already installed. I used three clips per inverter and the entire process only took 15 minutes!! It looks much nicer than the M190s! That part of the job likely took me over two hours with the M190s and required me lying face down on the roof while I cable-tied everything in place. And this approach will likely last for 25 years while the cable ties probably will ALL break long before then with no easy way to get in there to fix most of them. It's a big difference!
drees wrote:Does your layout facilitate center-tapping strings to effectively cut each string-length in half? That's another effective way to minimize the effects of cable length, especially if you use 10GA home-runs, though I guess with a voltage rise of only ~1V, it's not worth doing unless it shortened the cable run.
That's what I did with some of the M190 runs, but I don't know if I can do it with the M215s. In the old system, I had six strings of seven inverters, but only four roof penetrations and four breakers. So there are two pairs of strings which share a roof penetration, a junction box and a circuit breaker. I am not willing to add any more roof penetrations to accommodate the current change, since those were quite a bit of work and what is there is working out extremely well. For reference, here is a photograph of one of the old roof penetrations with two M190 strings feeding into it (click for larger image):

Image

The Engage cable replaced one of the strings that had its own circuit breaker, so it was not a problem to do. I *could* do a similar thing on the garage side where there is another penetration without a shared electrical connection with five inverters (and drop off two on the house side), but those are simply not as accessible. Likely I will just stick with putting 12 inverters on the single Engage cable and see what the inverters report for voltage at the end of the string.

Note also that the Engage cabling is *slightly* larger in diameter than the cabling for the M190s. So while I was able to fit two M190 cables into the 1" conduit I ran through the roof, I'm not sure whether I could fit two Engage cable through the same conduit. Here is a picture showing the two cables: M190 extension on the top and Engage on the bottom (click image to be able to read the text on the cables, you may need to click a second time to get full resolution in your browser):

Image
drees wrote:Keep in mind, though that the not all inverters benefit the same, it's primarily the inverters/panels farthest away from the junction box which benefit. So the 15th inverter in a string might see a significant reduction in voltage rise, the 1st one only sees a minimal difference.
Exactly. And even that calculation is for when the inverters are saturated at maximum power, which doesn't happen very often. Normally, it will be less. Plus, with the Engage system it is not a big deal, at least not in portrait orientation.
Last edited by RegGuheert on Fri Jun 27, 2014 1:57 pm, edited 2 times in total.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

kieranmullen
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 10:19 am

How often were you maxing out at 199W though. Do you realy believe it is a limitation of the inverters versus the panels themselves and available light? Historical usage would have helped determine if this was a sound investment or not.
RegGuheert wrote:Panels: Sharp NU-235F3 235W PV Modules
M190 Inverters: Enphase M190-72-240-S12 Microinverter
M215IG Inverters: Enphase M215-60-2LL-S22-IG Microinverter
.
- The M215 is *slightly* more efficient. I doubt I will see a real difference here, but we will see.
- The M215 can put out 225W while the M190 can only put out about 199W. This will not have any effect this time of year, but it should result in additional energy harvest in the cold of winter and spring.
2012 SL 5-29-14 6,000 Miles 6-16-15 24,562 (all bars)

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RegGuheert
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 11:28 am

kieranmullen wrote:How often were you maxing out at 199W though. Do you realy believe it is a limitation of the inverters versus the panels themselves and available light? Historical usage would have helped determine if this was a sound investment or not.
Yes, it is a limitation of the inverters. They have a specified maximum output power and they adjust the operating point of their power stage to stay below this output power. The peak power output of the PV panels times the inverter efficiency is significantly higher than the peak output power of the inverters. So on cold days when the sun is near the boresight of the array, the microinverters will limit.

But, as you say, this does not add up to much energy harvest lost through the course of a year. I don't know, but perhaps 30 to 100 kWh lost each year. It would take a LOT of years to pay for a $2000 investment at $10/year! But that's not the goal of this project. The goal is to press an old 2880W PV array back into service by providing those panels with microinverters. That should pay back the $2000 in about five years and should then pay us another $10,000 (or more) over the rest of the life of the inverters.

For those who may be interested, here is a plot of a very extreme case of clipping by the microinverters in our system (from April 2, 2013):

Image
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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RegGuheert
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Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 2:03 pm

Just to let everyone know, I've added images to some of the posts above. Please let me know if you would like to see any others.

When I was shooting the pictures, I also took the one below. Can anyone guess what that is at the bottom right of the photograph?

Image
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

kieranmullen
Posts: 276
Joined: Fri Aug 16, 2013 5:26 pm
Delivery Date: 16 Aug 2013
Leaf Number: 020781
Location: Hillsboro, oregon

Re: Enphase M190 vs. M215IG: Head-to-Head

Fri Jun 27, 2014 2:49 pm

Why do we have to guess? Is there some sort of prize involved? It appears to be an amphibian of some sort.
RegGuheert wrote:Just to let everyone know, I've added images to some of the posts above. Please let me know if you would like to see any others.

When I was shooting the pictures, I also took the one below. Can anyone guess what that is at the bottom right of the photograph?

Image
2012 SL 5-29-14 6,000 Miles 6-16-15 24,562 (all bars)

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